Universal joints enable rotary motion of two shafts arranged at different relative directions to be transmitted with the purpose of providing angular displacement between both shafts. Said devices are used typically (although not exclusively) in the field of motor vehicles to transmit rotary motion to the wheels when they are both driving and steered wheels at the same time, as well as in the steering columns in motor vehicles wherein motion is not possible to be transmitted through a single piece longitudinal shaft, especially due to the particular geometry of the interior of the motor vehicle where different mechanical parts of steering assembly are to be fitted and operated.
Mounting assemblies for fastening a driving shaft in such universal joints into yokes of said joints are known in the art. Said yokes have an open, usually U-shaped, configuration, in which wings respective holes are provided for receiving a clamp bolt.
Examples of said mounting assembly may be found in the state of the art, such as in the U.S. Pat. No. 6,350,078 which discloses a retaining member for the shaft of a joint in a steering column assembly of a motor vehicle. The retaining member is inserted into the stem of a bolt that is screwed up into in the holes of the yoke, transversely to the driving shaft. The retaining member is a cylindrical body that covers the whole bolt stem and that has a deformable outer surface in the form of circumferential or helical ridges radially projecting away from the outer surface thereof. When inserting the bolt into the sleeve an interference between the fins and the surface of the driving shaft takes place, thus causing that said fins become deformed.
The main disadvantage of this state of art mounting assembly is that the pressure exerted on the driving shaft by interference of such circumferential or helical fins does not allow a homogeneous load distribution thereon. Furthermore, as the sleeve covers the whole stem, seating of the assembly on the yoke is carried out by means of the sleeve, which does not have strength mechanical features suitable for this function, being apt to undergo a premature fatigue wear of the material in the assembly operation.